AJP - Endocrinology and Metabolism, Vol 269, Issue 2 E231-E238, Copyright © 1995 by American Physiological Society

ARTICLES

Effects of glucagon with or without insulin administration on liver glycogen metabolism

N. Ercan, M. C. Gannon and F. Q. Nuttall
Metabolic Research Laboratory, Minneapolis Veterans Affairs Medical Center, Minnesota, USA.

Rats fed ad libitum were given insulin alone (4 U/kg), glucagon alone (25 micrograms/kg), or insulin and glucagon sequentially. Phosphorylase a and synthase R activities, hepatic glycogen, uridine diphosphoglucose, inorganic phosphate (Pi), and plasma glucose, lactate, glucagon, and insulin concentrations were determined over the subsequent 40 min. In separate animals, muscle extraction of 2-deoxy-D-[3H]glucose also was determined. After glucagon administration, glycogen phosphorylase a and plasma glucose were increased within 5 min. However, the glycogen concentration did not decrease for 20 min. Glucagon administration to rats pretreated with insulin stimulated a similar increase in phosphorylase a activity. Again, glycogen was not degraded for 20 min. After insulin only, glycogen concentration remained unchanged. Plasma glucose decreased as expected. In each group, muscle extraction of 2-deoxy-D-[3H]glucose increased compared with the controls (P < 0.05). In summary, glucagon and/or insulin administration did not stimulate significant glycogen degradation for 20 min, even though phosphorylase was activated. The mechanism remains to be determined.

This article has been cited by other articles:

				K. Fosgerau, S. D. Mittelman, A. Sunehag, M. K. Dea, K. Lundgren, and R. N. Bergman Lack of hepatic "interregulation" during inhibition of glycogenolysis in a canine model Am J Physiol Endocrinol Metab, August 1, 2001; 281(2): E375 - E383. [Abstract] [Full Text] [PDF]

				N. G. Ercan-Fang, F. Q. Nuttall, and M. C. Gannon Uric acid inhibits liver phosphorylase a activity under simulated in vivo conditions Am J Physiol Endocrinol Metab, February 1, 2001; 280(2): E248 - E253. [Abstract] [Full Text] [PDF]

				D. Nethery, D. Stofan, L. Callahan, A. DiMarco, and G. Supinski Formation of reactive oxygen species by the contracting diaphragm is PLA2 dependent J Appl Physiol, August 1, 1999; 87(2): 792 - 800. [Abstract] [Full Text] [PDF]